pub fn resolve_shell(explicit: Option<&str>) -> Result<Shell>Expand description
Diagnostic helper for the CLI: detect or validate a shell from
the --shell CLI value, surfacing a clear error for unknown
shells. Returns the resolved Shell or a DodotError::Other.
When explicit is None and Shell::detect() returns None
(unsupported $SHELL), errors out asking the user to pass
--shell bash or --shell zsh. Better than silently falling
back to bash on a fish/nu setup, which would produce an alias
that never fires.